Tail gas waste heat recovery system and cogeneration equipment

Abstract

The utility model provides a tail gas waste heat recovery system and cogeneration equipment, the tail gas waste heat recovery system comprises a plurality of heat branches which communicate with a high-temperature tail gas exhaust pipe and are arranged side by side, at least one heat branch is a direct exhaust branch capable of directly communicating with the outside atmosphere, and at least two heat branches are heat recovery branches for supplying heat to a user side; a control valve used for controlling on-off and air flow is arranged in each hot branch. In this way, the number of the heat recovery branches is at least two, the transmission path of the high-temperature tail gas is effectively increased, and multi-stage utilization of the high-temperature tail gas at the user side is achieved; a control valve is arranged in each heat branch, only the target heat recovery branch can be selected to be opened according to the target heat use requirement, the air flow is regulated and controlled, and the flexible applicability is high; and the direct exhaust branch is arranged, and when the sum of energy provided by the high-temperature tail gas is larger than the sum of energy required by target heat utilization in the target heat recovery branch, the direct exhaust branch can be opened, and part of the high-temperature tail gas is exhausted.

Description

Technical Field

[0001] This application relates to the field of exhaust gas waste heat recovery technology, specifically to an exhaust gas waste heat recovery system and a combined heat and power (CHP) device. Background Technology

[0002] Solid oxide fuel cells (SOFCs) utilize electrochemical principles to efficiently and environmentally convert the chemical energy stored in fuel and oxidant into electrical energy at medium to high temperatures (600℃-800℃). An SOFC system consists of an anode, electrolyte, and cathode. High-temperature air is introduced to the cathode, where oxygen gains electrons and undergoes a reduction reaction to generate oxygen ions. These oxygen ions then pass through the electrolyte to the anode. High-temperature fuel gas (hydrogen, natural gas, alcohols, LPG, gasoline, diesel, etc.) introduced to the anode undergoes a reforming reaction inside the cell to generate H2, CO, CO2, etc. H2 and CO react with oxygen ions to generate electrons, which are then transferred to the cathode through an external medium, forming an electric current. SOFC systems have a power generation efficiency exceeding 50%, far surpassing traditional power plants. They also exhibit low noise and low pollution emissions, making them suitable for widespread application as distributed power sources in residential power generation, office buildings, shopping malls, and power plants.

[0003] SOFC systems operate at a high temperature of 800℃. In addition to the effective electrical work output, the high-temperature exhaust gas still contains a significant proportion of heat. However, in existing exhaust gas waste heat recovery systems, the high-temperature exhaust gas is often transported along a single path, resulting in low heat utilization efficiency and a substantial amount of heat loss. Utility Model Content

[0004] In view of this, this application provides a waste heat recovery system for exhaust gas, which can improve the heat utilization efficiency of high-temperature exhaust gas and avoid heat loss.

[0005] In addition, this application also provides a cogeneration device including the above-mentioned exhaust gas waste heat recovery system.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] A waste heat recovery system for recovering and utilizing high-temperature exhaust gas generated by a fuel cell system. The waste heat recovery system includes multiple heat branches connected to and parallel to the high-temperature exhaust pipe, wherein at least one of the heat branches is a direct discharge branch that can be directly connected to the outside atmosphere, and at least two of the heat branches are heat recovery branches that supply heat to the user end.

[0008] Each of the aforementioned hot branches is equipped with a control valve for controlling its on / off state and the amount of gas flow.

[0009] Optionally, in the above-mentioned exhaust gas waste heat recovery system, at least one of the heat branches is detachably connected to the exhaust gas waste heat recovery system.

[0010] Optionally, in the above-mentioned exhaust gas waste heat recovery system, the at least two heat recovery branches include a first heat recovery branch, which includes a first heat exchanger, a user water inlet pipeline for supplying user water to the first heat exchanger, and a user water outlet pipeline for supplying user water to the user end.

[0011] The first heat exchanger includes a first flow channel and a second flow channel. The first inlet of the first flow channel is connected to the high-temperature exhaust pipe, and the first outlet of the first flow channel is connected to the outside atmosphere. The second inlet of the second flow channel is connected to the user's water inlet pipe, and the second outlet of the second flow channel is connected to the user's water outlet pipe.

[0012] Optionally, in the above-mentioned exhaust gas waste heat recovery system, the first heat recovery branch further includes a first liquid storage tank, which is disposed between the second outlet and the user water outlet pipeline.

[0013] Optionally, in the above-mentioned exhaust gas waste heat recovery system, the at least two heat recovery branches include a second heat recovery branch, the second heat recovery branch includes a heat pump unit, the heat pump unit includes a second heat exchanger, and a circulating medium return pipeline and a circulating medium outlet pipeline for circulating the circulating medium of the heat pump unit in the second heat exchanger.

[0014] The second heat exchanger includes a third flow channel and a fourth flow channel. The third inlet of the third flow channel is connected to the high-temperature exhaust gas pipe, and the third outlet of the third flow channel is connected to the outside atmosphere. The fourth inlet of the fourth flow channel is connected to the circulating medium return pipe, and the fourth outlet of the fourth flow channel is connected to the circulating medium outlet pipe, so as to exchange heat between the high-temperature exhaust gas and the circulating medium, thereby raising the temperature of the circulating medium.

[0015] Optionally, in the above-mentioned exhaust gas waste heat recovery system, the heat pump unit further includes a third heat exchanger, and the circulating medium circulates between the second heat exchanger and the third heat exchanger through the circulating medium return pipeline and the circulating medium outlet pipeline;

[0016] The second heat recovery branch includes a heating medium return pipeline and a heating medium outlet pipeline that allow the heating medium to circulate between the third heat exchanger and the heating equipment at the user end.

[0017] The third heat exchanger includes a fifth flow channel and a sixth flow channel. The fifth inlet of the fifth flow channel is connected to the liquid outlet of the circulating medium, and the fifth outlet of the fifth flow channel is connected to the liquid return of the circulating medium. The sixth inlet of the sixth flow channel is connected to the liquid return of the heating medium, and the sixth outlet of the sixth flow channel is connected to the liquid outlet of the heating medium, so that the circulating medium, after being heated by heat exchange with the high-temperature exhaust gas, exchanges heat with the heating medium, thereby raising the temperature of the heating medium.

[0018] Optionally, in the above-mentioned exhaust gas waste heat recovery system,

[0019] The second heat recovery branch includes a second liquid storage tank, through which the heating medium outlet pipe and the heating medium return pipe respectively flow;

[0020] And / or,

[0021] The second heat recovery branch includes a circulation pump, which is installed in the heating medium return pipeline or the heating medium outlet pipeline to allow the heating medium to circulate between the third heat exchanger and the heating equipment.

[0022] And / or,

[0023] The heat pump unit includes a third liquid storage tank, which is located in the circulating medium return pipeline.

[0024] Optionally, in the above-mentioned exhaust gas waste heat recovery system,

[0025] The heat pump unit includes a compressor installed on the circulating medium outlet pipeline;

[0026] The heat pump unit includes an expansion valve connected to the return liquid pipeline of the circulating medium.

[0027] Optionally, in the above-mentioned exhaust gas waste heat recovery system,

[0028] A first temperature detector is installed on the outlet pipeline of the circulating medium; the exhaust gas waste heat recovery system also includes a first controller, which is used to control the opening degree of the expansion valve, and the first controller is connected to the first temperature detector and the expansion valve.

[0029] And / or,

[0030] A second temperature detector is installed on the outlet pipeline of the heating medium; the exhaust gas waste heat recovery system also includes a second controller, which is used to control the opening degree of the control valve on the second heat recovery branch, and the second controller is connected to the second temperature detector and the control valve.

[0031] A combined heat and power (CHP) device includes a fuel cell system and a waste heat recovery system for recovering and utilizing the high-temperature exhaust gas generated by the fuel cell system, wherein the waste heat recovery system is as described above.

[0032] As can be seen from the above, the exhaust gas waste heat recovery system and cogeneration equipment disclosed in this application are equipped with multiple heat branches, and at least two of these heat branches are heat recovery branches, which effectively increases the transmission path of high-temperature exhaust gas and realizes multi-stage utilization of high-temperature exhaust gas at the user end. Furthermore, each heat branch is equipped with a control valve, so a specific number of heat recovery branches that need to be opened can be selected, i.e., the target heat recovery branches can be selected. The flow rate of high-temperature exhaust gas in the target heat recovery branches can be adjusted by the control valve to control the target temperature of heat to be supplied to the user end, thereby meeting the target heat demand of the user end, which is highly flexible and applicable. In addition, at least one of the multiple heat branches is a direct exhaust branch that can be directly connected to the outside atmosphere. As mentioned above, when the total energy provided by the high-temperature exhaust gas discharged by the fuel cell system is large, while the total energy of the target heat demand is small, the direct exhaust branch can be opened to discharge part of the high-temperature exhaust gas, thereby meeting the target heat demand of the user end, further enhancing the flexibility and applicability. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the exhaust gas waste heat recovery system provided in the embodiments of this application;

[0035] Figure 2 A schematic diagram of the exhaust gas waste heat recovery system for removing the first heat recovery branch provided in an embodiment of this application;

[0036] Figure 3 A schematic diagram of the exhaust gas waste heat recovery system of the second heat recovery branch of the demolition section provided in another embodiment of this application;

[0037] Figure 4 A flowchart illustrating the temperature control of the heating medium in the second heat recovery branch provided in this application embodiment.

[0038] Figures 1-4 middle:

[0039] 1. Fuel cell system; 2. Exhaust gas waste heat recovery system; 3. Heating equipment;

[0040] 21. First heat recovery branch; 22. Second heat recovery branch; 23. Direct discharge branch; 24. First control valve; 25. Second control valve; 26. Third control valve;

[0041] 211. First heat exchanger; 212. User water outlet pipeline; 213. First storage tank; 214. User water inlet pipeline;

[0042] 221. Heat pump unit; 222. Heating medium return pipeline; 223. Heating medium outlet pipeline; 224. Second storage tank; 225. Second temperature detector; 226. Circulation pump;

[0043] 2211, Second heat exchanger; 2212, Third heat exchanger; 2213, Circulating medium return line; 2214, Circulating medium outlet line; 2215, Compressor; 2216, Expansion valve; 2217, First temperature detector; 2218, Third liquid storage tank. Detailed Implementation

[0044] This application provides a waste heat recovery system for exhaust gas and a combined heat and power (CHP) device.

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] like Figure 1-4 As shown, this application provides an exhaust gas waste heat recovery system 2, which is used to recover high-temperature exhaust gas generated by a fuel cell system 1. The fuel cell system 1 includes a high-temperature exhaust pipe that discharges the high-temperature exhaust gas. The exhaust gas waste heat recovery system 2 includes multiple heat branches, each connected to the high-temperature exhaust pipe, arranged in parallel. At least one heat branch is a direct exhaust branch 23 that can communicate with the outside atmosphere, and at least two heat branches are heat recovery branches that supply heat to the user end. Each heat branch is equipped with a control valve for controlling its on / off state and gas flow rate, so as to select and open a specific number of heat recovery branches according to the target heat demand, i.e., select a target heat recovery branch, which can be one or more, and adjust the gas flow rate of the high-temperature exhaust gas in the target heat recovery branch; and select whether to open the direct exhaust branch 23 according to the target heat demand, and adjust the gas flow rate of the high-temperature exhaust gas in the direct exhaust branch 23.

[0047] Optionally, the fuel cell system is a solid oxide fuel cell system. Solid oxide fuel cell (SOFC) is a third-generation fuel cell that uses solid oxide as the electrolyte and efficiently and environmentally friendly converts the chemical energy stored in the fuel and oxidant into electrical energy directly at medium to high temperatures. SOFCs are widely used as distributed power sources in home power generation, office buildings, shopping malls, power plants, etc. Fuel cell system 1 is a power generation system (no specific requirements) containing components such as fuel cells, heat exchangers, and burners. After the intake gas enters fuel cell system 1, it outputs electrical power and high-temperature exhaust gas. High-temperature exhaust gas: After the intake gas enters fuel cell system 1, it undergoes electrochemical reactions and internal heat exchange, and is discharged outside the system as exhaust gas with a temperature higher than room temperature.

[0048] Please see the appendix Figure 1-3 It should be noted that the control valve installed on the direct exhaust branch 23 is the third control valve 26. When the third control valve 26 is open, the high-temperature exhaust gas flows through the direct exhaust branch 23. During this process, the high-temperature exhaust gas does not participate in heat exchange with other media but is directly discharged into the outside atmosphere. When the control valve installed on the heat recovery branch is open, the high-temperature exhaust gas flows through the heat recovery branch. During this process, the high-temperature exhaust gas exchanges heat with the medium to be heated, causing the medium to heat up to become a high-temperature medium, and the high-temperature exhaust gas to cool down to a low-temperature exhaust gas. Then, the high-temperature medium is transported to the user end through the heat recovery branch to provide heating for the user, and the low-temperature exhaust gas is discharged into the outside atmosphere. The user end can be a home, hotel, etc.

[0049] It should be further clarified that when there is no air flow through the control valve, the control valve is in the open state; when there is air flow through the control valve, the control valve is in the connected state; when the control valve on the heat branch is open, the heat branch is in the closed state; when the control valve on the heat branch is connected, the heat branch is in the open state. "Target heat demand" refers to the clearly defined heat recovery branch that needs to be opened, and the clearly defined temperature at which the opened heat recovery branch needs to supply heat to the user end; the aforementioned heat recovery branch that needs to be opened is the target heat recovery branch, and the temperature at which the target heat recovery branch needs to supply heat to the user end is the target temperature. The target temperature can be a specific point value or a range with upper and lower deviations.

[0050] The selected target heat recovery branch and target temperature can be input via the command input structure. This input command is then transmitted to a controller capable of controlling the control valve. The controller opens the control valve on the target heat recovery branch and adjusts the airflow rate based on the target temperature. The temperature of the high-temperature exhaust gas flowing through the high-temperature exhaust pipe is compared with the target temperature. Based on this comparison, the controller determines whether to open the third control valve 26 and adjusts its flow rate: when the total energy provided by the high-temperature exhaust gas flowing through the high-temperature exhaust pipe exceeds the total energy required for the target heat demand, the controller connects the third control valve 26; otherwise, it disconnects. The larger the difference in the comparison, the greater the opening of the third control valve 26, resulting in a larger airflow rate through the direct exhaust branch 23. The command input structure can be a control panel that communicates with the controller.

[0051] The exhaust gas waste heat recovery system of this application is equipped with multiple heat branches, and at least two of these heat branches are heat recovery branches, which effectively increases the transmission path of high-temperature exhaust gas and realizes multi-level utilization of high-temperature exhaust gas at the user end. In addition, each heat branch is equipped with a control valve, so a specific number of heat recovery branches that need to be opened can be selected, i.e., the target heat recovery branches, to control the flow path of high-temperature exhaust gas. The flow rate of high-temperature exhaust gas in the target heat recovery branches can be adjusted by the control valve to control the target temperature of heat to be supplied to the user end, thereby meeting the target heat demand of the user end, which is highly flexible and applicable. Furthermore, at least one of the multiple heat branches is a direct exhaust branch 23 that can be directly connected to the outside atmosphere. As mentioned above, when the total energy provided by the high-temperature exhaust gas discharged by the fuel cell system 1 is large, while the total energy of the target heat demand is small, the direct exhaust branch 23 can be opened to discharge part of the high-temperature exhaust gas, thereby meeting the target heat demand of the user end, further enhancing the flexibility and applicability.

[0052] In some embodiments of this application, at least one heat branch is detachably connected to the exhaust waste heat recovery system, so that only the target heat recovery branch is connected according to the target heat demand, while the other heat recovery branches are not connected to the exhaust waste heat recovery system; and it is determined whether the direct exhaust branch 23 needs to be connected according to the target heat demand, or the direct exhaust branch 23 is always connected to the exhaust waste heat recovery system.

[0053] It should be noted that "the hot branch is connected to the exhaust gas waste heat recovery system" means that all the pipes that make up the hot branch, as well as all the heat exchange components installed on the above-mentioned pipes, are accurately connected, and the hot branch is connected to the high-temperature exhaust gas pipe.

[0054] Optionally, in some embodiments, each heat recovery branch is detachably connected to the exhaust gas waste heat recovery system. Optionally, in other parallel embodiments, only at least two heat recovery branches (i.e., all heat recovery branches) are detachably connected to the exhaust gas waste heat recovery system, so that only the target heat recovery branch can be connected according to the target heat demand.

[0055] As mentioned above, different heat branches can be flexibly switched or combined according to the target heat demand, enabling the exhaust gas waste heat recovery system to be dynamically adjusted and highly flexible and applicable. Furthermore, only the target heat recovery branch is connected, while unnecessary heat branches are no longer connected, which maximizes the simplification of the exhaust gas waste heat recovery system's structure, saves unnecessary pipelines, heat exchange devices, etc., and reduces system costs.

[0056] Please see the appendix Figure 1 , 3 In some embodiments of this application, at least two heat recovery branches include a first heat recovery branch 21, which includes a first heat exchanger 211, a user water inlet pipe 214, and a user water outlet pipe 212. The user water inlet pipe 214 is used to supply user water to the first heat exchanger 211, and the user water outlet pipe 212 is used to supply user water to the user end. The first heat exchanger 211 includes a first flow channel and a second flow channel. The first inlet of the first flow channel is connected to a high-temperature exhaust pipe, and the first outlet of the first flow channel is connected to the outside atmosphere. The second inlet of the second flow channel is connected to the user water inlet pipe 214, and the second outlet of the second flow channel is connected to the user water outlet pipe 212.

[0057] It should be noted that the control valve installed on the first heat recovery branch 21 is the first control valve 24. The low-temperature user water is the medium to be heated in the first heat recovery branch 21. The low-temperature user water flows to the user water inlet pipe 214; the high-temperature exhaust gas exchanges heat with the low-temperature user water in the first heat exchanger 211, causing the low-temperature user water to heat up to high-temperature user water, and the high-temperature exhaust gas to cool down to low-temperature exhaust gas; the high-temperature user water flows to the user end through the user water outlet pipe 212 to provide hot water supply.

[0058] Optionally, the user's water can be municipal water, which can be groundwater or tap water, to ensure the supply of hot water for bathing in homes or hotels during winter (selection based on user needs).

[0059] As mentioned above, by using the waste heat of the high-temperature exhaust gas flowing to the first heat recovery branch 21 to heat the user's water, the energy utilization rate can be significantly improved, fuel consumption can be reduced, thereby reducing the user's water heating cost and providing the user with an economical and environmentally friendly hot water heating solution.

[0060] Please see the appendix Figure 1 ,3 In some embodiments of this application, the first heat recovery branch 21 further includes a first liquid storage tank 213, which is disposed between the second outlet and the user water outlet pipeline 212.

[0061] As mentioned above, the first liquid storage tank 213 can store user water after heating to provide a stable hot water supply and avoid water temperature instability or insufficient supply caused by instantaneous demand fluctuations. In addition, the first liquid storage tank 213 can also balance the system load, reduce the frequent start-up and shutdown of the first heat recovery branch 21, extend the system life and improve energy efficiency. Furthermore, the first liquid storage tank 213 can serve as an emergency backup to ensure basic water demand in the event of system failure, while reducing energy waste, lowering operating costs and achieving energy conservation and environmental protection.

[0062] Please see the appendix Figure 1-2 In some embodiments of this application, at least two heat recovery branches include a second heat recovery branch 22, which includes a heat pump unit 221. The heat pump unit 221 includes a second heat exchanger 2211, and a circulating medium return pipe 2213 and a circulating medium outlet pipe 2214 for circulating the circulating medium of the heat pump unit 221 through the second heat exchanger 2211. The second heat exchanger 2211 includes a third flow channel and a fourth flow channel; the third inlet of the third flow channel is connected to the high-temperature exhaust gas pipe, and the third outlet of the third flow channel is connected to the outside atmosphere; the fourth inlet of the fourth flow channel is connected to the circulating medium return pipe 2213, and the fourth outlet of the fourth flow channel is connected to the circulating medium outlet pipe 2214, so that the high-temperature exhaust gas exchanges heat with the circulating medium, thereby raising the temperature of the circulating medium.

[0063] It should be noted that the control valve installed on the second heat recovery branch 22 is the second control valve 25. The low-temperature circulating medium delivered to the second heat exchanger 2211 via the circulating medium return pipeline 2213 is the medium to be heated in the second heat recovery branch 22. The high-temperature exhaust gas exchanges heat with the low-temperature circulating medium in the second heat exchanger 2211, causing the low-temperature circulating medium to heat up to a high-temperature circulating medium, and the high-temperature exhaust gas to cool down to a low-temperature exhaust gas; the high-temperature circulating medium then flows out through the circulating medium outlet pipeline 2214, so that the high-temperature circulating medium exchanges heat with the user-end medium for heating the user-end medium.

[0064] In addition to the first heat recovery branch 21, this application also adds a second heat recovery branch 22 parallel to the first heat recovery branch 21. High-temperature exhaust gas can be transmitted along multiple paths, realizing multi-stage utilization of the high-temperature exhaust gas and improving heat utilization efficiency. Furthermore, in the second heat recovery branch 22, the high-temperature exhaust gas does not directly exchange heat with the user-end medium; instead, a heat pump unit 221 is added. The heat pump unit 221 can achieve more precise temperature control. Because the heat pump unit 221 has excellent automatic control and regulation functions, it can stably maintain the temperature of the user-end medium within the set target temperature range, avoiding instability in the user-end medium temperature due to fluctuations in the high-temperature exhaust gas temperature, thereby improving the stability and comfort of user-end medium heating.

[0065] Please see the appendix Figure 1-2 In some embodiments of this application, the heat pump unit 221 further includes a third heat exchanger 2212, and the circulating medium circulates between the second heat exchanger 2211 and the third heat exchanger 2212 through a circulating medium return pipe 2213 and a circulating medium outlet pipe 2214. The second heat recovery branch 22 includes a heating medium return pipe 222 and a heating medium outlet pipe 223 that circulate the heating medium between the third heat exchanger 2212 and the heating equipment 3 at the user end. The third heat exchanger 2212 includes a fifth flow channel and a sixth flow channel; the fifth inlet of the fifth flow channel is connected to the circulating medium outlet pipe 2214, and the fifth outlet of the fifth flow channel is connected to the circulating medium return pipe 2213; the sixth inlet of the sixth flow channel is connected to the heating medium return pipe 222, and the sixth outlet of the sixth flow channel is connected to the heating medium outlet pipe 223, so that the circulating medium, after being heated by heat exchange with the high-temperature exhaust gas, exchanges heat with the heating medium, thereby raising the temperature of the heating medium.

[0066] The low-temperature heating medium, described above, is transported to the third heat exchanger 2212 via the heating medium return pipeline 222. The high-temperature circulating medium and the low-temperature heating medium exchange heat in the third heat exchanger 2212, causing the low-temperature heating medium to heat up to a high-temperature heating medium, and the high-temperature circulating medium to cool down to a low-temperature circulating medium. The high-temperature heating medium then flows to the heating equipment 3 via the heating medium outlet pipeline 223, causing the heating equipment 3 to heat up. The heating equipment 3 exchanges heat with the surrounding air, causing the surrounding air to heat up. Optionally, the second heat recovery branch 22 can ensure the heating supply of the heating equipment 3 in homes or hotels during winter.

[0067] As mentioned above, in the second heat recovery branch 22, the high-temperature exhaust gas first exchanges heat with the circulating medium of the heat pump unit 221, and the heated circulating medium then exchanges heat with the heating medium. The heat pump unit 221 can achieve more precise temperature control of the circulating medium, thereby stably maintaining the temperature of the heating medium that directly exchanges heat with the circulating medium within the set target temperature range. This avoids the drawback of unstable heating medium temperature caused by high-temperature exhaust gas temperature fluctuations, thereby improving the stability and comfort of the heating equipment 3.

[0068] Please see the appendix Figure 1-2 In some embodiments of this application, the second heat recovery branch 22 includes a second liquid storage tank 224, and the heating medium outlet pipe 223 and the heating medium return pipe 222 flow through the second liquid storage tank 224 respectively.

[0069] As mentioned above, the second liquid storage tank 224 can store the heating medium after heating and balance the system load, accurately meet the temperature of the heating medium required by the heating equipment 3, and thus ensure the stability and comfort of the heating equipment 3.

[0070] Please see the appendix Figure 1-2 In some embodiments of this application, the second heat recovery branch 22 includes a circulation pump 226, which is installed in the heating medium return line 222 or the heating medium outlet line 223 to circulate the heating medium between the third heat exchanger 2212 and the heating equipment 3. Optionally, the circulation pump 226 is installed in the heating medium return line 222. By installing the circulation pump 226, a stable and reliable circulation of the heating medium can be ensured, thereby ensuring the stability and comfort of the heating provided by the heating equipment 3.

[0071] Please see the appendix Figure 1-2 In some embodiments of this application, the heat pump unit 221 includes a third liquid storage tank 2218, which is disposed in the circulating medium return pipeline 2213. The circulating medium can be stored in the third liquid storage tank 2218, and the flow rate of the circulating medium in the circulation path can be adjusted according to the heat demand, which is highly flexible and applicable.

[0072] In some embodiments of this application, the heat pump unit 221 includes a compressor 2215 disposed on the circulating medium outlet pipeline 2214. After the circulating medium absorbs heat from the high-temperature exhaust gas and vaporizes, it enters the compressor 2215. Then, the compressor 2215 performs work, transforming the low-temperature, low-pressure circulating medium into a high-temperature, high-pressure circulating medium gas. As described above, the compressor 2215 further increases the temperature of the circulating medium, achieving precise and flexible control over the temperature rise of the circulating medium.

[0073] Furthermore, the heat pump unit 221 includes an expansion valve 2216 connected to the circulating medium return line 2213. After the circulating medium is cooled down by heat exchange with the heating medium, it enters the third storage tank 2218. The circulating medium in the third storage tank 2218 flows through the expansion valve 2216 and is throttled and depressurized to form a low-temperature, low-pressure wet steam circulating medium. The flow rate of the circulating medium can be adjusted by regulating the opening of the expansion valve 2216 to prevent overheating and optimize system performance, ensuring the efficient and stable operation of the heat pump unit 221.

[0074] Please see the appendix Figure 1-2 In some embodiments of this application, a first temperature detector 2217 is provided on the circulating medium outlet pipe 2214. The exhaust gas waste heat recovery system also includes a first controller, which is used to control the opening degree of the expansion valve 2216. The first controller is connected to the first temperature detector 2217 and the expansion valve 2216. Further, the first controller is electrically connected or wirelessly communicated with the first temperature detector 2217 and the expansion valve 2216. The first temperature detector 2217 is provided close to the outer wall surface of the circulating medium outlet pipe 2214; the first temperature detector 2217 may be a sensible heat storage device.

[0075] The first temperature detector 2217 is used to detect the temperature of the circulating medium after heat exchange and heating with the high-temperature exhaust gas in the second heat exchanger 2211. This temperature is designated as the first temperature. The first temperature detector 2217 transmits the detected first temperature to the first controller, which compares the first temperature with the target temperature.

[0076] When the first temperature is greater than the target temperature, it indicates that the temperature of the circulating medium is too high. At this time, the first controller sends a command to the expansion valve 2216 to increase the opening of the expansion valve 2216. The flow rate of the circulating medium through the expansion valve 2216 increases, which reduces the temperature of the circulating medium after throttling, thereby making the first temperature equal to the target temperature.

[0077] When the first temperature is less than the target temperature, it indicates that the temperature of the circulating medium is too low. At this time, the first controller sends a command to the expansion valve 2216 to reduce the opening of the expansion valve 2216. The flow rate of the circulating medium through the expansion valve 2216 is reduced, which increases the temperature of the circulating medium after throttling, thereby making the first temperature equal to the target temperature.

[0078] By setting the first temperature detector 2217, the temperature of the circulating medium after heat exchange and heating can be detected in real time, thereby automatically and accurately controlling the temperature of the circulating medium to ensure that it meets the target temperature.

[0079] In some embodiments of this application, a second temperature detector 225 is provided on the heating medium outlet pipe 223. The exhaust gas waste heat recovery system also includes a second controller, which is used to control the opening degree of the second control valve 25. The second controller is connected to the second temperature detector 225 and the second control valve 25. Further, the second controller is electrically connected or wirelessly communicated with the second temperature detector 225 and the second control valve 25. The second temperature detector 225 is installed close to the outer wall surface of the heating medium outlet pipe 223; the second temperature detector 225 may be a sensible heat storage device.

[0080] The second temperature detector 225 is used to detect the temperature of the heating medium after it has been heated by heat exchange with the circulating medium in the third heat exchanger 2212. This temperature is designated as the second temperature. The second temperature detector 225 transmits the detected second temperature to the second controller, which compares the second temperature with the target temperature.

[0081] When the second temperature is greater than the target temperature, it proves that the temperature of the heating medium is too high. At this time, the second controller sends a command to the second control valve 25 to reduce the opening of the second control valve 25, thereby reducing the flow rate of the high-temperature exhaust gas flowing into the second heat exchanger 2211, thereby reducing the temperature of the circulating medium after heat exchange with the high-temperature exhaust gas, and thus reducing the temperature of the heating medium after heat exchange with the circulating medium, so that the second temperature meets the target temperature.

[0082] When the second temperature is less than the target temperature, it indicates that the temperature of the heating medium is too low. At this time, the second controller sends a command to the second control valve 25 to increase the opening of the second control valve 25, thereby increasing the flow rate of the high-temperature exhaust gas flowing into the second heat exchanger 2211, thereby increasing the temperature of the circulating medium after heat exchange with the high-temperature exhaust gas, and thus increasing the temperature of the heating medium after heat exchange with the circulating medium, so that the second temperature meets the target temperature.

[0083] By setting a second temperature detector 225, the temperature of the heating medium after heat exchange and heating can be detected in real time, thereby automatically and accurately controlling the temperature of the heating medium to ensure that it meets the target temperature.

[0084] It should be noted that the first controller and the second controller can be two independent controllers, an integrated controller, or the same controller.

[0085] Of course, in addition to setting the first heat recovery branch 21 and the second heat recovery branch 22, other heat recovery branches can be set according to actual needs. There is no specific limit to the number of other heat recovery branches set; it can be one, two, or more.

[0086] Example 1

[0087] Please see the appendix Figure 1 The exhaust gas waste heat recovery system includes three heat branches connected to the high-temperature exhaust pipe. At this time, the high-temperature exhaust gas discharged through the high-temperature exhaust pipe has three flow paths:

[0088] 1) First heat recovery branch 21: The high-temperature exhaust gas pipe is connected to the inlet of the first control valve 24 installed on the first heat recovery branch 21. The outlet of the first control valve 24 is connected to the first inlet of the first flow channel of the first heat exchanger 211, and the first outlet of the first flow channel is connected to the outside atmosphere. The user water inlet pipe 214 is connected to the second inlet of the second flow channel of the first heat exchanger 211. The second outlet of the second flow channel is connected to the inlet of the first liquid storage tank 213, and the outlet of the first liquid storage tank 213 is connected to the user water outlet pipe 212.

[0089] 2) Second heat recovery branch 22: The high-temperature exhaust pipe is connected to the inlet of the second control valve 25 installed on the second heat recovery branch 22. The outlet of the second control valve 25 is connected to the third inlet of the third flow channel of the second heat exchanger 2211. The third outlet of the third flow channel is connected to the outside atmosphere.

[0090] 3) Direct exhaust branch 23: The high-temperature exhaust pipe is connected to the inlet of the third control valve 26 installed on the direct exhaust branch 23, and the outlet of the third control valve 26 is connected to the outside atmosphere.

[0091] Furthermore, in 2) above:

[0092] The third liquid storage tank 2218 stores liquid circulating medium. The outlet of the third liquid storage tank 2218 is connected to the inlet of the expansion valve 2216 via a circulating medium return pipe 2213. The outlet of the expansion valve 2216 is connected to the fourth inlet of the fourth flow channel of the second heat exchanger 2211 via the circulating medium return pipe 2213. The fourth outlet of the fourth flow channel is connected to the inlet of the compressor 2215 via a circulating medium outlet pipe 2214 (a first temperature detector 2217 is installed on the outer wall of the circulating medium outlet pipe 2214 between the fourth outlet and the compressor 2215). The outlet of the compressor 2215 is connected to the fifth inlet of the fifth flow channel of the third heat exchanger 2212 via the circulating medium outlet pipe 2214. The fifth outlet of the fifth flow channel is connected to the inlet of the third liquid storage tank 2218 via the circulating medium return pipe 2213. The first temperature detector 2217 is communicatively connected to the controller, and the controller is communicatively connected to the expansion valve 2216 to control the opening degree of the expansion valve 2216.

[0093] The second storage tank 224 stores liquid heating medium. The low-temperature outlet of the second storage tank 224 is connected to the sixth inlet of the sixth flow channel of the third heat exchanger 2212 via a heating medium return pipe 222. The sixth outlet of the sixth flow channel is connected to the high-temperature inlet of the second storage tank 224 via a heating medium outlet pipe 223. The high-temperature outlet of the second storage tank 224 is connected to the inlet of the heating device 3 via the heating medium outlet pipe 223 (a second temperature detector 225 is installed on the outer wall of the heating medium outlet pipe 223 between the high-temperature outlet of the second storage tank 224 and the inlet of the heating device 3). The outlet of the heating device 3 is connected to the low-temperature inlet of the second storage tank 224 via the heating medium return pipe 222. The second temperature detector 225 is communicatively connected to a controller, which is communicatively connected to a second control valve 25 to control the opening degree of the second control valve 25.

[0094] The working process of this exhaust gas waste heat recovery system is as follows:

[0095] The high-temperature exhaust pipe of the fuel cell system 1 is connected to the first heat recovery branch 21. The high-temperature exhaust gas exchanges heat with the user water in the first heat exchanger 211 of the first heat recovery branch 21, so that the user water is heated to meet the target heat demand. The heated user water is stored in the first liquid storage tank 213 for hot water supply.

[0096] The high-temperature exhaust pipe of fuel cell system 1 is connected to the second heat recovery branch 22. Based on the first temperature detected by the first temperature detector 2217 and the set target temperature, the opening of the expansion valve 2216 is adjusted, thereby adjusting the flow rate of the circulating medium and reducing the pressure of the circulating medium. The circulating medium in the third liquid storage tank 2218 forms a low-temperature and low-pressure wet steam circulating medium after passing through the expansion valve 2216. The wet steam circulating medium enters the second heat exchanger 2211 and exchanges heat with the high-temperature exhaust gas at a certain flow rate (the gas flow rate is adjusted by the opening of the second control valve 25). After absorbing the heat from the high-temperature exhaust gas, the circulating medium vaporizes and enters the compressor 2215. Then, after the compressor 2215 does work, the low-temperature and low-pressure circulating medium becomes a high-temperature and high-pressure gas circulating medium. The high-temperature and high-pressure gas circulating medium enters the third heat exchanger 2212, liquefies and releases heat, exchanges heat with the heating medium, increases the temperature of the heating medium, and stores the heated heating medium in the second liquid storage tank 224 to provide hot water for the heating equipment 3. The second temperature detector 225 is installed on the outer wall of the heating medium outlet pipe 223 between the high temperature outlet of the second liquid storage tank 224 and the inlet of the heating equipment 3, and is used to detect the water temperature supplied by the second liquid storage tank 224 to the heating equipment 3.

[0097] Please see the appendix Figure 4 The temperature control process for the circulating medium in the second heat recovery branch 22 is as follows:

[0098] 1) Given the opening degree of a second control valve 25;

[0099] 2) Determine whether the first temperature detected by the first temperature detector 2217 meets the requirements based on the set target temperature. If it does not meet the requirements, adjust the opening of the expansion valve 2216 (increase the opening of the expansion valve 2216 if the first temperature is greater than the target temperature, and decrease the opening of the expansion valve 2216 if the first temperature is less than the target temperature) until the requirements are met, i.e., until the first temperature equals the target temperature. If the requirements are met, determine whether the second temperature detected by the second temperature detector 225 meets the requirements.

[0100] 3) Determine whether the second temperature detected by the second temperature detector 225 meets the requirements based on the set target temperature: if it does not meet the requirements, adjust the opening of the second control valve 25 (if the second temperature is greater than the target temperature, decrease the opening of the second control valve 25; if the second temperature is less than the target temperature, increase the opening of the second control valve 25), and repeat step 2) until the requirements are met, that is, until the second temperature equals the target temperature.

[0101] 4) Once the requirements are met, maintain the adjusted parameters for operation;

[0102] 5) If it is necessary to adjust the water temperature supplied to the heating equipment 3 by the second liquid storage tank 224, make the adjustment again according to the above steps.

[0103] The opening of the first control valve 24 can be adjusted according to the target temperature required by the user water in the first storage tank 213. If the actual water temperature of the user water in the first storage tank 213 is greater than the target temperature, the opening of the first control valve 24 is reduced; otherwise, the opening of the first control valve 24 is increased.

[0104] When the total energy required for the target heat of the first heat recovery branch 21 and the second heat recovery branch 22 is less than the total energy that the high-temperature exhaust gas discharged from the high-temperature exhaust pipe can provide, the third control valve 26 is connected to directly discharge the excess high-temperature exhaust gas to the outside atmosphere; otherwise, the third control valve 26 is disconnected.

[0105] When the total energy required for the target heat demand of the first heat recovery branch 21 and the second heat recovery branch 22 is greater than the total energy that the high-temperature exhaust gas discharged from the high-temperature exhaust pipe can provide, and the user needs to use both the first heat recovery branch 21 and the second heat recovery branch 22 at the same time, the hot water supply for the user's water in the first heat recovery branch 21 will be given priority, while the energy missing in the heating supply of the second heat recovery branch 22 can be provided by the power consumption of the compressor 2215.

[0106] Example 2

[0107] Please see the appendix Figure 2If the user only needs to meet the heating supply of the heating equipment 3, the first heat recovery branch 21 can be removed based on the first embodiment.

[0108] Example 3

[0109] Please see the appendix Figure 3 If the user only needs to meet the hot water supply requirement, the second heat recovery branch 22 can be removed based on the first embodiment.

[0110] In summary, this application also provides a cogeneration device, which includes a fuel cell system 1 and a waste heat recovery system for recovering and utilizing the high-temperature exhaust gas generated by the fuel cell system 1. The waste heat recovery system is the waste heat recovery system 2 described above.

[0111] Since the cogeneration equipment of this application includes the exhaust gas waste heat recovery system 2 described above, the beneficial effects of the cogeneration equipment brought by the exhaust gas waste heat recovery system 2 can be found above and will not be repeated here.

[0112] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0113] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0114] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0115] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0116] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0117] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A waste heat recovery system for exhaust gas, used to recover and utilize high-temperature exhaust gas generated by a fuel cell system, characterized in that, The exhaust gas waste heat recovery system includes multiple heat branches connected to and parallel to the high-temperature exhaust gas pipe, wherein at least one of the heat branches is a direct discharge branch that can be directly connected to the outside atmosphere, and at least two of the heat branches are heat recovery branches that supply heat to the user end. Each of the aforementioned hot branches is equipped with a control valve for controlling its on / off state and the amount of gas flow.

2. The exhaust gas waste heat recovery system according to claim 1, characterized in that, At least one of the heat branches is detachably connected to the exhaust gas waste heat recovery system.

3. The exhaust gas waste heat recovery system according to claim 1, characterized in that, The at least two heat recovery branches include a first heat recovery branch, which includes a first heat exchanger, a user water inlet pipeline for supplying user water to the first heat exchanger, and a user water outlet pipeline for supplying user water to the user end. The first heat exchanger includes a first flow channel and a second flow channel. The first inlet of the first flow channel is connected to the high-temperature exhaust pipe, and the first outlet of the first flow channel is connected to the outside atmosphere. The second inlet of the second flow channel is connected to the user's water inlet pipe, and the second outlet of the second flow channel is connected to the user's water outlet pipe.

4. The exhaust gas waste heat recovery system according to claim 3, characterized in that, The first heat recovery branch also includes a first liquid storage tank, which is located between the second outlet and the user water outlet pipeline.

5. The exhaust gas waste heat recovery system according to claim 1, characterized in that, The at least two heat recovery branches include a second heat recovery branch, the second heat recovery branch includes a heat pump unit, the heat pump unit includes a second heat exchanger, and a circulating medium return pipe and a circulating medium outlet pipe for circulating the circulating medium of the heat pump unit in the second heat exchanger. The second heat exchanger includes a third flow channel and a fourth flow channel. The third inlet of the third flow channel is connected to the high-temperature exhaust gas pipe, and the third outlet of the third flow channel is connected to the outside atmosphere. The fourth inlet of the fourth flow channel is connected to the circulating medium return pipe, and the fourth outlet of the fourth flow channel is connected to the circulating medium outlet pipe, so as to exchange heat between the high-temperature exhaust gas and the circulating medium, thereby raising the temperature of the circulating medium.

6. The exhaust gas waste heat recovery system according to claim 5, characterized in that, The heat pump unit also includes a third heat exchanger, and the circulating medium circulates between the second heat exchanger and the third heat exchanger through the circulating medium return pipe and the circulating medium outlet pipe; The second heat recovery branch includes a heating medium return pipeline and a heating medium outlet pipeline that allow the heating medium to circulate between the third heat exchanger and the heating equipment at the user end. The third heat exchanger includes a fifth flow channel and a sixth flow channel. The fifth inlet of the fifth flow channel is connected to the liquid outlet of the circulating medium, and the fifth outlet of the fifth flow channel is connected to the liquid return of the circulating medium. The sixth inlet of the sixth flow channel is connected to the liquid return of the heating medium, and the sixth outlet of the sixth flow channel is connected to the liquid outlet of the heating medium, so that the circulating medium, after being heated by heat exchange with the high-temperature exhaust gas, exchanges heat with the heating medium, thereby raising the temperature of the heating medium.

7. The exhaust gas waste heat recovery system according to claim 6, characterized in that, The second heat recovery branch includes a second liquid storage tank, through which the heating medium outlet pipe and the heating medium return pipe respectively flow; And / or, The second heat recovery branch includes a circulation pump, which is installed in the heating medium return pipeline or the heating medium outlet pipeline to allow the heating medium to circulate between the third heat exchanger and the heating equipment. And / or, The heat pump unit includes a third liquid storage tank, which is located in the circulating medium return pipeline.

8. The exhaust gas waste heat recovery system according to any one of claims 5-7, characterized in that, The heat pump unit includes a compressor installed on the circulating medium outlet pipeline; The heat pump unit includes an expansion valve connected to the return liquid pipeline of the circulating medium.

9. The exhaust gas waste heat recovery system according to claim 8, characterized in that, A first temperature detector is installed on the outlet pipeline of the circulating medium; the exhaust gas waste heat recovery system also includes a first controller, which is used to control the opening degree of the expansion valve, and the first controller is connected to the first temperature detector and the expansion valve. And / or, A second temperature detector is installed on the outlet pipeline of the heating medium; the exhaust gas waste heat recovery system also includes a second controller, which is used to control the opening degree of the control valve on the second heat recovery branch, and the second controller is connected to the second temperature detector and the control valve.

10. A combined heat and power (CHP) device, characterized in that, The invention includes a fuel cell system and a waste heat recovery system for recovering and utilizing the high-temperature exhaust gas generated by the fuel cell system, wherein the waste heat recovery system is the waste heat recovery system as described in any one of claims 1-9.

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